Motor-driven power tools and the like have conventionally been connected to a commercial AC power source, a DC constant-voltage power source, and the like, but a growing number of power tools are now equipped with secondary batteries. Power tools employing secondary batteries are also referred to as cordless power tools. As these power tools continue to expand in type and application, a demand for greater battery capacity increases. While a battery pack for powering these power tools has traditionally been mounted directly in a body of the tool, a waist-belt-type power supply has also been proposed. This power supply accommodates rechargeable batteries in a waist belt that can be worn about the user's waist (for example, see Japanese Utility Model Application Publication No. H07-3983).